Documentation
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Overview ¶
Package log is a replacement for the standard library log package that logs to OTEL spans contained in Context objects. These are seen as events with the attribute "log" set to true.
The preferred way to log is to use an event:
func someFunc(ctx context.Context) {
e := NewEvent("someFunc()")
defer e.Done(ctx)
start := time.Now()
defer func() {
e.Add("latency.ns", int(time.Since(start)))
}()
}
This records an event in the current span that has a key of "latency.ns" with the value in nano-seconds the operation took.
You can use this to log in a similar manner to the logging package with Println and Printf. This is generally only useful for some generic debugging where you want to log something and filter the trace by messages with key "log". Generally these are messages you don't want to keep.
func main() {
ctx := context.Background()
log.SetFlags(log.LstdFlags | log.Lshortfile)
log.Println(ctx, "Starting main")
log.Printf(ctx, "Env variables: %v", os.Environ())
}
The above won't log anything, as there is no Span on the Context. If there was it would get output to the Open Telementry provider.
If you need to use the standard library log, you can use Logger:
log.Logger.Println("hello world")
This would print whever the stanard logger prints to. This defaults to the standard logger, but you can replace with another Logger if you wish.
You should only log messages with a standard logger when it can't be output to a trace. These are critical messages that indicate a definite bug. This keeps logging to only critical events and de-clutters what you need to look at to when doing a debug.
Index ¶
Constants ¶
const ( Ldate = 1 << iota // the date in the local time zone: 2009/01/23 Ltime // the time in the local time zone: 01:23:23 Lmicroseconds // microsecond resolution: 01:23:23.123123. assumes Ltime. Llongfile // full file name and line number: /a/b/c/d.go:23 Lshortfile // final file name element and line number: d.go:23. overrides Llongfile LUTC // if Ldate or Ltime is set, use UTC rather than the local time zone LstdFlags = Ldate | Ltime // initial values for the standard logger )
Variables ¶
var Logger *log.Logger = log.Default()
Logger provides access to the standard library's default logger. This can be replaced in main with a logger of your choice.
Functions ¶
Types ¶
type Event ¶
type Event struct {
// contains filtered or unexported fields
}
Event represents a named event that occurs. This is the prefered way to log data. Events have attributes and those attributes are key/value pairs. You create an event and stuff attributes using Add() until the event is over and call Done(). This will render the event to the current span. if no attrs exist, the event is ignored. To avoid extra allocations
Source Files